Temporally Adaptive Shading Reuse for Real-Time Rendering and Virtual Reality

Abstract

Temporal coherence has the potential to enable a huge reduction of shading costs in rendering. Existing techniques focus either only on spatial shading reuse or cannot adaptively choose temporal shading frequencies. We find that temporal shading reuse is possible for extended periods of time for a majority of samples, and we show under which circumstances users perceive temporal artifacts. Our analysis implies that we can approximate shading gradients to efficiently determine when and how long shading can be reused. Whereas visibility usually stays temporally coherent from frame to frame for more than 90%, we find that even in heavily animated game scenes with advanced shading, typically more than 50% of shading is also temporally coherent. To exploit this potential, we introduce a temporally adaptive shading framework and apply it to two real-time methods. Its application saves more than 57% of the shader invocations, reducing overall rendering times up to in virtual reality applications without a noticeable loss in visual quality. Overall, our work shows that there is significantly more potential for shading reuse than currently exploited.